Generally, an electroosmotic dehydrator is an apparatus that is applied with a direct current power supply for forming electric field to remove water coupled with sludge by electrophoretic property and dehydrates water contained in the sludge by means of a voltage difference.
The structure comprises a drum largely applied with a + and −; a caterpillar applied with + or − pole by being mounted to be spaced by a constant space portion from the drum; and a filter cloth belt wound for transfer and dehydration of sludge between the drum and the caterpillar.
Herein, there may be an electroosmotic dehydrator comprising an electrode plate applied with − or +, which rotates at an endless track such as the caterpillar, instead of the caterpillar.
Such a conventional electroosmotic dehydrator applies constant pure direct current voltage between the drum and the caterpillar (or electrode plate) to form electric field and transfers water around liquid sludge particles charged in the electric field to an electrode opposite to a charge taken by the sludge particles by means of electrophoresis and capillary phenomena to separate and remove water.
In other words, since the sludge particles have − surface charge, if the electric field is applied to the sludge, the sludge particles move to a positive (+) pole and the water in the sludge particle layer moves to a negative (−) pole, thereby promoting the dehydration.
However, since such a conventional electroosmotic dehydrator has a structure that the drum is made of only stainless, an electrochemical reaction occurs by the electric field generating between the drum and the caterpillar (or electrode plate) when performing the dehydrating work so that the surface of the drum is electrolyzed, thereby causing large and small corrosion on the surface thereof.
And, the drum is heated at high temperature by means of coulombic heating generated between the drum and the caterpillar (or electrode plate) to generate vapor, thereby causing more serious corrosion on the surface of the drum as well as a change in an external form.
Therefore, the use lifetime of the drum is shortened more than expected, the electrical conductivity of the drum is degraded, and the dehydration performance is degraded, thereby causing problems that maintenance cost of the dehydrator is increased, power consumption required for the operation of the dehydrator is increased, and water content of the sludge is increased.